How can I make all the junk calls stop?? (Several times a day, always about "my car warranty"... I have never owned a car.)

They come from different numbers so I can’t just block a single number, but they always leave the same automated voicemail that my car warranty may have expired. They’re coming to an AT&T cell phone (I never had any junk calls on my Sprint phone). I hesitate to call AT&T because they have been horrible w/ other customer service and I don’t expect this is their responsibility.

What could be the difference and how could I make this stop? This is a new number for a phone that I got three months ago. I don’t get any junk calls except from this @#$%$ car warranty place.